SUMMARY Photoreceptor (PR) degeneration is a leading cause of blindness worldwide, and remains poorly understood. A leading cause of PR degeneration is thought to be damage instilled by reactive oxygen species (ROS). PRs are also some of the most highly metabolic cells in the body, and this high aerobic metabolism is a strong source of ROS. How PRs develop such high aerobic capacity, and how PRs balance this capacity with excess ROS, is not known. We propose here to test the hypotheses that 1) the dramatic developmental increase in PR mitochondrial metabolism seen during post-natal development is mediated by the transcriptional coactivators PGC- 1alpha and beta, known potent regulators of mitochondrial metabolism in other cells; and 2) PGC-1alpha and beta simultaneously regulate an anti-ROS program that can be usurped to slow PR degeneration. We will test these hypotheses with novel genetic mouse models, and with state-of-the-art approaches for gene delivery to the eye. Success in these studies may open new avenues for therapeutic intervention in these devastating diseases.